AUSTIN, Texas — With 34 states now requiring some form of identification at the polls, former president Bill Clinton and civil rights leader Andrew Young on Wednesday endorsed the idea of adding photos to Social Security cards as a way to prevent voter suppression.

The two made the recommendation in separate appearances at a conference at the Lyndon B. Johnson presidential library, which is commemorating the 50th anniversary of the passage of the Civil Rights Act.

The three-day event, at which President Barack Obama and former president George W. Bush will speak on Thursday, has brought new attention to Johnson’s domestic policy legacy, which has been overshadowed in public opinion by his role in escalating the Vietnam War.

Clinton compared Johnson’s role to that of Abraham Lincoln, and said the Civil Rights Act and the 1965 Voting Rights Act passed “because of President Johnson’s brilliant, pivotal leadership.”

It represented, Clinton said, the “power of the presidency to redeem the promise of America. . . . He knew what the presidency was for.”

That kind of embrace has long eluded the 36th president, even from members of his own party. When Clinton appeared at the Johnson library as a presidential candidate in 1992, he gave a speech in which he did not even mention Johnson’s name.

Clinton and Young, a former mayor of Atlanta, expressed concern that the voter ID laws could discourage poor and minority voters from showing up at the polls, which would circumvent the intent of the Voting Rights Act.

“I’m not against photo identification, but only as long as the cards are free and easily accessible. Providing eligible voters the ability to obtain a photo on a Social Security card eliminates any genuine concern,” Young said. He called on Obama to issue an executive order making such photos available.

Clinton did not go so far as to urge executive action. However, he said, putting photos on Social Security cards would represent “a way forward that eliminates error,” without having to “paralyze and divide a country with significant challenges.”